The present invention relates to novel xanthine derivatives. The derivatives are specific antagonists against adenosine A.sub.1 receptor which exhibit diuretic activity and renal protecting activity.
Xanthine derivatives have been hitherto known in the prior art. For example, U.S. Pat. No. 5,068,236 (Japanese Published Unexamined Patent Application No. 173888/91) discloses xanthine derivatives of the formula (A): ##STR4## wherein R.sup.A and R.sup.B are the same or different and are lower alkyl, and R.sup.C and R.sup.D are substituted or unsubstituted alicyclic alkyl. The xanthine derivatives exhibit diuretic activity, renal protecting activity and vasodilator activity.
EP 415456A (Japanese Published Unexamined Patent Application No. 173889/91) discloses xanthine derivatives of the formula (B): ##STR5## wherein R.sup.A and R.sup.B are the same as defined above; and Q.sup.A represents ##STR6## (in which n.sup.a is 0 or 1, and Y.sup.A represents a single bond or alkylene). The xanthine derivatives exhibit diuretic activity, renal protecting activity and bronchodilator activity.
EP 369744A (Japanese Published Unexamined Patent Application No. 178283/90) discloses xanthine derivatives of the formula (C): ##STR7## wherein R.sup.E and R.sup.F are cycloalkyl; m1.sup.a and m2.sup.a are an integer of 0 to 3; and R.sup.G is hydrogen, alkyl, alkenyl, alkynyl, or cycloalkyl. The xanthine derivatives inhibit phosphodiesterases and exhibit cerebro-protective activity.
EP 389282A (Japanese Published Unexamined Patent Application No. 273676/90) discloses xanthine derivatives of the formula (D): ##STR8## wherein R.sup.E, R.sup.F, m1.sup.a and m2.sup.a are the same as defined above; and R.sup.H is halogen, nitro, or ##STR9## (in which R.sup.I and R.sup.J each independently represent hydrogen, alkyl, or alkylcarbonyl, or R.sup.I and R.sup.J together with the nitrogen to which they are attached form an optionally substituted heterocyclic group). The xanthine derivatives inhibit phosphodiesterases and exhibit antiallergic activity.